Re: [PATCH] powerpc: EOI spurious irqs during boot so they can be reenabled later
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From: miltonm <hidden>
Date: 2008-08-06 02:55:57
----- Original Message Follows ----- From: Michael Ellerman <redacted> To: Paul Mackerras <redacted> Cc: <redacted>, Milton Miller [off-list ref], Segher Boessenkool [off-list ref] Subject: [PATCH] powerpc: EOI spurious irqs during boot so they can be reenabled later Date: Wed, 6 Aug 2008 12:03:37 +1000 (EST)
In the xics code, if we receive an irq during boot that hasn't been setup yet - ie. we have no reverse mapping for it - we mask the irq so we don't hear from it again. Later on if someone request_irq()'s that irq, we'll unmask it but it will still never fire. This is because we never EOI'ed the irq when we originally received it - when it was spurious. This can be reproduced trivially by banging the keyboard while kexec'ing on a P5 LPAR, even though the hvc_console driver request's the console irq, the console is non-functional because we're receiving no console interrupts.
which means some driver didn't disable interrupts on its shutdown, but I digress.
So when we receive a spurious irq mask it and then EOI it. Signed-off-by: Michael Ellerman <redacted> --- arch/powerpc/platforms/pseries/xics.c | 29 ++++++++++++++++++++--------- 1 files changed, 20 insertions(+), 9 deletions(-) Updated to mask then EOI, thanks to Segher for whacking me with the clue stick.
Actually, just sending the EOI would likely result in the exact same interrupt comming back, as the mask will set a bit near the source but the interrupt would have already been missed. (most irqs in xics systems are level). Thanks to segher for noticing the order. However...
quoted hunk
diff --git a/arch/powerpc/platforms/pseries/xics.cb/arch/powerpc/platforms/pseries/xics.c index 0fc830f..4c692b2 100644 --- a/arch/powerpc/platforms/pseries/xics.c +++ b/arch/powerpc/platforms/pseries/xics.c @@ -321,21 +321,26@@ static unsigned int xics_startup(unsigned int virq) return 0; } +static void xics_eoi_hwirq_direct(unsigned int hwirq) +{ + iosync(); + direct_xirr_info_set((0xff << 24) | hwirq); +} + static void xics_eoi_direct(unsigned int virq) { - unsigned int irq = (unsigned int)irq_map[virq].hwirq; + xics_eoi_hwirq_direct((unsignedint)irq_map[virq].hwirq); +} +static void xics_eoi_hwirq_lpar(unsigned int hwirq) +{ iosync(); - direct_xirr_info_set((0xff << 24) | irq); + lpar_xirr_info_set((0xff << 24) | hwirq); } - static void xics_eoi_lpar(unsigned int virq) { - unsigned int irq = (unsigned int)irq_map[virq].hwirq; - - iosync(); - lpar_xirr_info_set((0xff << 24) | irq); + xics_eoi_hwirq_lpar((unsigned int)irq_map[virq].hwirq); } static inline unsigned int xics_remap_irq(unsigned int vec) @@ -350,9 +355,15 @@ static inline unsigned int xics_remap_irq(unsigned int vec) if (likely(irq != NO_IRQ)) return irq; - printk(KERN_ERR "Interrupt %u (real) is invalid," - " disabling it.\n", vec); + pr_err("%s: no mapping for hwirq %u, disabling it.\n" , __func__, vec); + xics_mask_real_irq(vec); + + if (firmware_has_feature(FW_FEATURE_LPAR)) + xics_eoi_hwirq_lpar(vec); + else + xics_eoi_hwirq_direct(vec); + return NO_IRQ; }
I really dislike this great big if in the middle of a function. we called this function from two different call sites where the choice of which to call was based on their environment. Please move the call to eoi the hwirq to the callers, who know which path to take. I guess it might make sense to put the printk in a mask_invalid_real_irq wrapper, and then perhaps just duplicate the small remaining code? Or split the return of spurious from NO_IRQ (ie should spurious be NO_IRQ_IGNORE?)
-- 1.5.5